out of the following the correct statement(s) is/are (a) Number of subshells present in M-shell is equal to 3, (b) maximum number of electrons present in l shell is equal to 8, (c) number of electron present in subshell is `3(2l + 1)`, (d) `Cu^+` is paramagnetic

Options

A. (a),(b) &(c)
B. (b) & (d)
C. (a)&(b)
D. (a), (b), (c) & (d)

Answer

To determine which statements are correct, let's analyze each statement step by step.

### Step 1: Analyze Statement (a)
**Statement (a): Number of subshells present in M-shell is equal to 3.**

- The M-shell corresponds to the principal quantum number \( n = 3 \).
- The number of subshells in a shell is given by the values of the azimuthal quantum number \( l \), which can take values from \( 0 \) to \( n-1 \).
- For \( n = 3 \), \( l \) can be \( 0, 1, 2 \) (which correspond to the s, p, and d subshells respectively).
- Therefore, the number of subshells in the M-shell is \( 3 \) (s, p, and d).

**Conclusion for Statement (a): Correct.**

### Step 2: Analyze Statement (b)
**Statement (b): Maximum number of electrons present in L-shell is equal to 8.**

- The L-shell corresponds to the principal quantum number \( n = 2 \).
- The maximum number of electrons in a shell can be calculated using the formula \( 2n^2 \).
- For \( n = 2 \):
\[ \text{Maximum electrons} = 2(2^2) = 2 \times 4 = 8 \]

**Conclusion for Statement (b): Correct.**

### Step 3: Analyze Statement (c)
**Statement (c): Number of electrons present in subshell is \( 3(2l + 1) \).**

- The formula for the maximum number of electrons in a subshell is actually \( 2(2l + 1) \), not \( 3(2l + 1) \).
- For example, for \( l = 0 \) (s subshell), maximum electrons = \( 2(2 \times 0 + 1) = 2 \).
- For \( l = 1 \) (p subshell), maximum electrons = \( 2(2 \times 1 + 1) = 6 \).
- For \( l = 2 \) (d subshell), maximum electrons = \( 2(2 \times 2 + 1) = 10 \).

**Conclusion for Statement (c): Incorrect.**

### Step 4: Analyze Statement (d)
**Statement (d): \( Cu^+ \) is paramagnetic.**

- The electronic configuration of copper (Cu) is \( [Ar] 4s^1 3d^{10} \).
- When it loses one electron to form \( Cu^+ \), the configuration becomes \( [Ar] 3d^{10} \).
- Since all electrons in \( 3d^{10} \) are paired, \( Cu^+ \) is actually diamagnetic, not paramagnetic.

**Conclusion for Statement (d): Incorrect.**

### Final Conclusion:
The correct statements are:
- (a) Number of subshells present in M-shell is equal to 3.
- (b) Maximum number of electrons present in L-shell is equal to 8.

### Summary of Correct Statements:
- **Correct Statements**: (a) and (b)
- **Incorrect Statements**: (c) and (d)

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